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Subido el 28 de mayo de 2007 por EducaMadrid

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Fourth segment of NASA Connect Hidden Treasures explaining what archaeologists do. This segment covers how archaelogists reconstructed the historic environments of the Mayan and their agriculture practices. Archaelogists try to use the information from the past farming practice of the Mayan to save the rain forests.

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When you think of an archaeologist, what do you picture? 00:00:00
Someone just digging spearheads, or maybe pottery, or writing down the words of some 00:00:06
primitive tribe? 00:00:10
My name is Tom Seaver, and I'm a NASA archaeologist, and what I do is try to understand why human 00:00:11
cultures succeed and why they fail. 00:00:17
I also excavate artifacts in an attempt to understand the ancient past. 00:00:19
These artifacts consist of ceramic bowls, of bone material, and of spearheads, lithic, 00:00:24
stone material. 00:00:29
More importantly, what I do is examine the soil structures to try to understand and reconstruct 00:00:30
prehistoric environments and ancient climate patterns. 00:00:36
Where the Patan Rainforest of Guatemala now stands, a great civilization once flourished, 00:00:40
the Maya. 00:00:45
The Maya built vast cities, ornate temples, and towering pyramids. 00:00:46
At its height, around 850 A.D., the population numbered 500 people per square mile in rural 00:00:51
areas and more than 2,000 people per square mile in the cities, comparable to modern-day 00:00:57
Los Angeles County. 00:01:02
The Maya initially depended on a type of farming known as slash and burn, which means exactly 00:01:04
what it sounds like. 00:01:09
In order to grow crops, such as corn, they would completely cut away, or slash, the dense 00:01:11
jungle vegetation, exposing soil for planting crops. 00:01:16
They would burn the debris that had been cleared. 00:01:20
Initially, ash from the burned debris gives the soil its fertility, but within three to 00:01:22
five years, the soil becomes exhausted, forcing the farmer to move on and cut down a new section. 00:01:28
Eventually, slash and burn would not support the large population of the Maya, so they 00:01:34
developed new agricultural techniques. 00:01:39
We are trying to determine exactly what these techniques were. 00:01:42
Without trees, erosion worsened, carrying away fertile topsoil. 00:01:46
Topsoil is the fertile layer of soil with enough nutrients to support healthy plant 00:01:51
growth. 00:01:55
In the rainforest, this layer of soil is very thin. 00:01:57
Slash and burn agriculture is being practiced in Guatemala today, and many researchers like 00:02:01
myself feel that this technique of agriculture is affecting local climate today in the area. 00:02:06
Our computer models suggest that when the forest is completely cut down, the temperature 00:02:12
of a region can rise five to six degrees. 00:02:16
If the Maya had completely deforested the region, the warmer temperatures would have 00:02:20
dried out the land, making it very difficult for raising crops. 00:02:24
Rising temperatures would also have disrupted rainfall patterns. 00:02:29
During the dry season in the Paten, water is scarce, and the groundwater is too deep, 00:02:33
500 feet deep, to tap with wells. 00:02:39
The Maya must have relied on rainwater saved in reservoirs to survive, so a disruption 00:02:42
in rainfall could have a terrible consequence on their ability to grow food. 00:02:47
Even when the Maya filled up all their reservoirs, they only had an 18-month supply. 00:02:52
A two- or a three-year drought would have had a devastating effect on them. 00:02:57
Remember what I said about the lack of trees causing erosion? 00:03:02
Archaeologists have also studied samples of soil from ancient lake sediment in the Paten 00:03:06
forest region. 00:03:11
In these samples of sediment, they have discovered tree pollen. 00:03:12
The curious part of all of this is that around 1,200 years ago, just before the Maya civilization's 00:03:16
disappearance, tree pollen disappeared almost completely and was replaced by the pollen 00:03:22
of weeds. 00:03:27
In other words, the region became almost completely deforested. 00:03:28
Did the Maya experience a natural drought that was made worse by the deforestation of 00:03:32
their environment? 00:03:38
A lot of researchers think that this is exactly what happened at 800 AD. 00:03:39
However, there is a bigger question. 00:03:45
The Maya survived for centuries in the delicate tropical forest of Central America. 00:03:47
Exactly how did they do it? 00:03:53
An important clue comes from space. 00:03:54
Data collected from satellites orbiting the Earth show evidence of an ancient system of 00:03:57
canals and irrigation ditches in low-lying swamps called bajos, the Spanish word for 00:04:01
low-lying. 00:04:07
Today's residents make little use of the bajos. 00:04:08
For years, archaeologists believe that the Maya hadn't used these swampy areas either. 00:04:11
During the rainy season from June to December, the bajos are too muddy and in the dry season 00:04:16
they're parched. 00:04:21
Neither condition is good for farming. 00:04:22
Not only do I use data collected from satellites, I also practice what is called ground-truthing. 00:04:25
Using a coordinate grid system, I am able to create maps of where I think I might find 00:04:31
evidence of the Maya canals and irrigation ditches. 00:04:36
Using satellite images, I explore the Earth up close to see that my data matches what 00:04:39
I can observe on the ground. 00:04:44
Data collected through remote sensing and ground-truthing have led archaeologists to 00:04:46
hypothesize that these ancient canals and habitation sites were part of a system devised 00:04:50
by the Maya to manage water in the ancient bajos and to use these areas for farming. 00:04:56
The bajos make up almost half of the region. 00:05:01
By making good use of the bajos for farming, the Maya would have been able to grow a much 00:05:04
larger and more dependable supply of food. 00:05:08
They could have farmed the bajos during the dry season by draining the water to lower 00:05:12
areas into reservoirs. 00:05:16
This way, they could have had two crops on the elevated ridges during the rainy season 00:05:18
and two crops during the dry season in the bajos. 00:05:23
It is the evidence of these features in the bajos that is leading researchers and environmentalists 00:05:25
to help the people of the Patan rainforest today. 00:05:30
One goal of our NASA research is to see if we can rediscover how the ancient Maya used 00:05:34
this environment successfully. 00:05:39
If we can determine the agricultural techniques that they used, we can use those techniques 00:05:41
and apply them to modern-day populations who are living in the area today. 00:05:46
By learning what the Maya did right and what they did wrong, maybe we can help local people 00:05:54
find sustainable ways to farm the land while stopping short of the excesses that doomed 00:05:59
the Maya. 00:06:05
Using satellite data to examine Mayan ruins gives Seaver a big-picture view otherwise 00:06:06
impossible from his perspective here on Earth. 00:06:12
Combining remotely sensed or satellite data with conventional down-in-the-dirt archaeological 00:06:15
findings and working with NASA climate scientists, he may have uncovered a clue that will solve 00:06:21
one of history's greatest mysteries, as well as provide clues about what will happen to 00:06:27
our Earth in the future. 00:06:32
Wow. 00:06:34
You know, right now, as you watch this show, the rainforest is still falling under the 00:06:35
axe. 00:06:40
About half of the original rainforest has been destroyed in the past 40 years, cut down 00:06:42
by farmers practicing slash-and-burn agriculture. 00:06:47
This cycle repeats endlessly, or until the forest is gone. 00:06:51
By 2020, only 2 percent to 16 percent of the original rainforest will remain if current 00:06:55
rates of destruction continue. 00:07:02
Changes in cloud formation and rainfall are occurring over deforested parts of Central 00:07:04
America today. 00:07:09
Is history repeating itself? 00:07:11
If the residents of the rainforest cannot learn to live with their environment, many 00:07:14
scientists believe history will, in fact, repeat itself. 00:07:18
The bottom line is, how well do we, can we relate to our environment? 00:07:22
As we seek to explore new worlds, such as Mars, we are taking our cues from the mistakes 00:07:27
of the past. 00:07:33
Before sending humans to create colonies, NASA has a carefully planned series of uncrewed 00:07:34
missions designed to observe the environment of Mars. 00:07:40
Now, these missions are looking for water, testing the atmosphere, and monitoring the 00:07:43
cycles of weather. 00:07:48
Armed with as much detailed information as possible, future explorers and colonists to 00:07:50
the Red Planet will have a better understanding of how to work with their environment before 00:07:56
they arrive. 00:08:01
They will be much better prepared for survival than were the Jamestown colonists in 1607. 00:08:02
In fact, it is very likely that you are sitting among some of the first explorers and colonists 00:08:08
of Mars. 00:08:15
That's right. 00:08:16
NASA predicts that they will put humans on Mars as early as 30 years from now. 00:08:17
So here's my challenge to you, the next generation of explorers. 00:08:23
How can you learn from the past mistakes we've made here on Earth and apply that information 00:08:28
to making better decisions for your future exploration of new worlds? 00:08:33
Well that wraps up another episode of NASA Connect. 00:08:39
We'd like to thank everyone who helped make this program possible. 00:08:41
If you have a comment, question, or suggestion, well then email them to connect at lark.nasa.gov. 00:08:45
And don't forget to check out this program's student challenge. 00:08:52
You can find it on the NASA Connect website. 00:08:55
So until next time, stay connected to math, science, technology, and NASA. 00:08:58
Goodbye for now. 00:09:03
NASA Jet Propulsion Laboratory, California Institute of Technology 00:09:15
NASA Jet Propulsion Laboratory, California Institute of Technology 00:09:45
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Idioma/s:
en
Materias:
Matemáticas
Niveles educativos:
▼ Mostrar / ocultar niveles
      • Nivel Intermedio
Autor/es:
NASA LaRC Office of Education
Subido por:
EducaMadrid
Licencia:
Reconocimiento - No comercial - Sin obra derivada
Visualizaciones:
673
Fecha:
28 de mayo de 2007 - 16:54
Visibilidad:
Público
Enlace Relacionado:
NASAs center for distance learning
Duración:
09′ 47″
Relación de aspecto:
4:3 Hasta 2009 fue el estándar utilizado en la televisión PAL; muchas pantallas de ordenador y televisores usan este estándar, erróneamente llamado cuadrado, cuando en la realidad es rectangular o wide.
Resolución:
480x360 píxeles
Tamaño:
58.74 MBytes

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